Medical imaging, including X-ray, magnetic resonance (MR), computed tomography (CT), ultrasound, and various combinations of these techniques are utilized to provide images of internal patient structure for diagnostic purposes as well as for interventional procedures. One application of medical imaging (e.g., 3D imaging) is the measurement of volume and/or assessment of shape of internal structures of interest. These measurements typically require segmentation of image data, to separate structures of interest from the background, such that accurate calculations may be made.
One area where measurement of shape and volume is utilised is in the detection of prostate cancer. As will be appreciated, prostate cancer is one of the most common types of cancer among American men. Typically for a physician to diagnose prostate cancer, a biopsy of the prostate is performed. Biopsies are typically performed on patients that have either a suspect digital rectal exam (DRE) or abnormal PSA levels. PSA or ‘prostate-specific antigen’ is a protein produced by the cells of the prostate gland. A PSA test measures the level of PSA in the blood. In this regard, a doctor takes a blood sample, and the amount of PSA is measured in a laboratory.
Volume assessment of the prostate is an important and integral part of the decision to perform a biopsy. That is, the decision to perform biopsy in patients with abnormal PSA levels can be bolstered by PSA density (PSAD), which is defined as the PSA level divided by the prostate volume. In this regard, an expected PSA value may be based at least in part on the volume of a given prostate volume. The volume of the prostate gland can also be used to determine treatment options. Accordingly, it is important to identify the boundaries of the prostate from a medical image such that an accurate volume determination of the prostate can be made.
In addition, biopsy of the prostate requires guidance to a desired location. Such guidance may be provided by transrectal ultrasound imaging (TRUS). In such an application, a 3D image of the prostate may be generated to allow guidance of a biopsy needle to a prostate location of interest. As with volume determination, it is important that the boundaries of the prostate are identified from a medical image in order to allow for accurate biopsy guidance.
Unfortunately, boundary identification (e.g., segmentation) inn medical images is sometimes difficult. Even manual segmentation of medical images, such as ultrasound images, is difficult given the low signal to noise ratio and the presence of imaging artifacts.